Tuning the Li/Ni Disorder of the NMC811 Cathode by Thermally Driven Competition between Lattice Ordering and Structure Decomposition

Ni rich layered LiNixMnyCozO2 (NMC) cathodes for Lithium ion batteries (LIBs) are receiving great attentions owing to their promising large capacity, whereas the high content of Ni brings several issues including poor thermal stability and serious Li/Ni disorder. Although a little degree of Li/Ni disorder may be beneficial for structural stability of NMC cathodes and even Li ions’ migration, the high degree of Li/Ni disorder certainly deteriorates their electrochemical performances. Therefore, tuning the Li/Ni disorder is of great interest in development of safer NMC cathodes with larger accessible capacity. Post-synthesis annealing is a facile and low cost way to manipulate lattice defects, yet has not been utilized to optimize the Ni-rich NMC cathodes. In this work, we report that post-synthesis annealing can induce the competition between lattice ordering and structure decomposition. The thermal annealing promoted lattice ordering would prevail until the decomposition of oxygen lattice. Once the anneal...